Feed mechanism for disk recording machines



Oct. 18, 1938. L. THOMPSON FEED MECHANISM FOR DISK RECORDING MACHINES Filed April 23, 1936 2 Sheets-Sheet 1 a I v II" INVENTOR Lmcoln Thompson ATTORN EY Oct. 18, 2938. L THOMPSON 2,133,596

FEED MECHANISM FOR DISK RECORDING MACHINES Filed April 23, 1956 2 Sheets-Sheet 2 m iga 3| g2 ig 5 2e 64 x u Lm k A 5 y 5o M 6 f 20 fi M M l 1 23 D 22 ,W 6

am ENToR ATTORN EY Patented Oct. 18, 1938 H I r, 2,133,596

' UNITED f sr-Arss PAT-EN [oi-"nos FEED MECHANISM FOR DISK RECORDING Lincoln Thompson, Cheshire, Conn. I

mutation Apr-i123, 1936, semi N... 15,923 d I lo m '(ciz'ii-iayfl i This in'ventionrelate's to the art of sound receeding 150 per inch. Inprevious machines for cording. and more particularly to a machine for recording ph -disk records, the spacing of-the recording sound on soft disk records having grooves or tracks was, apt to be uneven 'due' means for producing a uniform spiral track on to backlash in the radial feed mechanism,'re 1 5 the record without unevenness due to backlash. sulting in an unsatisfactory reproduction of the "6 One object of this invention is to produceamessage, running together of grooves,"as'well a .s sound recording machine of the above nature difficulty in keeping the reproducing needle in having a swinging recording arm which is fed the groove. By means of the present invention,

slowly across the record by means of a worm" the above and other disadvantages have been lo drive receiving power at greatly reduced speed overcome.

from the'turntable shaft. Y Referring now to the drawings in whichiike A further object is to provide a recording mareference numerals denote corresponding parts chine of the above nature in which the backlash throughout the several views, the'numeral ID inbetween --the driving mechanism and the I redicates the top of a phonograph'recording cabil5 cording arm is taken up by a pair of differential net having an electric motor, not shown. for l frictionslippingunits. driving a large horizontal groovedpulley ii at- A further object is to provide a sound record tached to the lower end of a vertical spindle I2 ing machine of the above nature which will'be (see Fig. 2). The upper end of the spindle [2 simple in construction, inexpensive tomanu extends through the top ll of the cabinet and facture, easy to install and manipulate, comcarries aturntable it upon which is adapted to 20 pact, rugged, precise, ornamental in appearance, rest a diskrecord ll to be embossed or cut. Pivand durable in use. I i otally mounted in one corner of the top iii of the With there and other objects in view, there cabinet at one side of'the turntable; i3 is a radial v has been illustrated on the accompanying drawrecording arm li'which is connected at its inner :5 ings one form in which the invention ma be end to adrl'ven power head i6 passing upwardly conveniently embodied in practice. 1 through a'circular aperture H in the cabinet top In the'drawingsz I In and adapted to swing saidjarm l5 slowly Fig. 1 represents a perspective view of the across the-record ll. disk recording machine as it appears whenin The opposite or free end of the radial arm i an operation. I l5 supports a recording or cutting head which Fig. 2 is a side elevation of the recording arm is adiustably and pivotally secured thereto in a and the driving mechanism therefor, with a manner to be later described, and saidhead carv portion of said arm broken away to show the ries a detachable stylus-l9 for producing the interior construction. sound track in the record. 7 85 Fig. '3 is a vertical transverse sectional vie 'Ihe'transmission of power from the-motor to of the driving head of the radial recording'arm, the radial arm i5 is effected through a pair of p the view taken along the line 3-3 of Fig. 2. gear boxes-designated A and B (Fig. 2). The

Fig.4 is ahorizontal'sectional view ofthe same, gear box A isassociated with the drive spindle the view taken-along the line 4-4 of Fig. 3 look- 12, while the gear box B is associated with the 40 ing in the direction of the arrows. v I powerhead l6. The vertical drive spindle i2 40 Fig. 5 is a vertical sectional view taken along (Fig. 5) is journaled in a vertical bearing bushthe line 5-5 of Fig.2, showing a portion of the ing 'MI'having arelatively large flanged disk 20a driving mechanism and the turntable spindle. I integral with the upper end thereof and rigidly Fig. 6 is a horizontal sectional view ofthe attached tothe underside of'the cabinet top I0, I same, the view being taken along the line 6-6 as by screws 2i (Fig. 2). 45 of Fig. 5.. The spindle I2 is provided intermediate its Fig. '7 is a transverse sectional view of the relength with a worm 22 which is adapted to intercording arm taken along the line 1-1 of Fig. 2', mesh with a worm gear 23 positioned in a vertiand showing the micrometer adjustable counte'r-'- cal plane and enclosed in a square housing 24 balance mechanism for thecutting head. 1 located adjacent the bushing 20, said housing: be- 50 In the recording of spoken messages as well. ing'attached to the underside of the flanged disk as music it is often desirable to-condense as 200. A cover member 25 (Figs. 2 and 6) closes many words or sounds on the record as possible, the open end of the square housing 24 and. is necessitating quite close spacing of the grooves held in place by horizontal screws 26 positioned 66 or tracks, the number of such grooves often exin the corners thereof. 5!

The worm gear 28 is made rigid to a short stud shaft 21 by means ofa transversepin 28. said shaft 21 being suitably iournaled in a pair of flanged bushings 2! and 30 located respectively in the housing 24 and the cover member. 25. The rotation of the worm gear 23 is adapted to be opposed by a pair of frictional slipping disks 3i and 32 positioned on opposite sides of said gear wheel 24, each of said disks being formed of a series of built up leather washers. The pressure of the disks II and 32 against the opposite sides of the gear wheel" is controlled by means of the adjustable cover plate 25 which engages against the adjacent friction disk 32 and is preferably positioned in a slightly spaced relation from the square housing 24 and adapted to be adjustabiy drawn therea'gainst by means of the binding screws 2' previously mentioned. It is to be understood, however, that the friction disks 8i and 82 may in some cases be dispensed with if desired, within the general spirit and scope of the invention.

One exposed end of the stud shaft 21 is fixed to. one end of a horizontal elongated tubular shaft 83 by a pin 34 (see Fig. 6). The opposite end of the shaft a is connected to a stud shaft I. in thegear box B by a transverse pin ll (see Fig. 4). The studshaft 36 carries a worm 21 which is rotatable in a suitable bore 38 of a gear housing block I. and said shaft 35 is adapted to enter said bore through a flanged bearing bushing 4...

The worm 3'! intermeshes witha large horizontal worm gear (Figs. 3 and 4) keyed to a vertical driving spindle 42 of the power head it by .means of a tapered pin 43. The worm gear 4| is positioned within a horizontal cylindrical socket 44 formed within the housing block 39, and said socket 44 is adapted to be closed by a cover plate 45 superimposed thereupon and serving as a Journal for the upper end of the shaft 42. The lower end of the shaft 42 is suitably iournaled in a flanged bushing 48 provided in a suitable aperture in the block 38.

A relatively heavy flat elongated tie plate 41 is attached to the underside of the housing block 38 by means of a plurality of long vertical screws 44 passing through said plate 41 and said block 1!, and being threadediy engaged in allned tapped holes in the cover plate 45. The tie plate 41 serves to connect the gear box B with the gear box A and is supported upon the underside of the cabinet top I! by means of a pair of spaced hanger blocks 49 and 50, as shown in Fig. 2.

As shown in Pig. 3, the upper end of the driving spindle 42 has a flat plate Ii rigidly secured thereto by means of a transverse pin 52, and a relatively thick frictional disk 53 is interposed between said plate II and the cover plate 45. The disk plate ii is adapted to be pulled downwardly at all timu against the friction disk 53 by means of a strong helical spring 84 surrounding a lower reduced portion 55 of the spindle 42. The upper end of the spring 54 abuts against the flanged bushing 46 while the lower end abuts aka-inst, a washer it and an adjusting nut 61 mounted on a threaded section of the reduced portion I of the spindle, whereby the pressure of said plate 5| upon the friction disk 83 may be manually adJusted as desired.

The friction plate I is provided on its outer edge with an upstanding integral flange 58 which serves to deflne a seat for the power head or hub ",the latter having an interior hollow chamber 59, and being attached to said plate ll by means of screws B0, 84, as shown in Fig. 3. The rear end of the radial arm ii is superimposed on the hub l6 and is adiustably held thereagainst by means of a flanged stud 62 having a reduced threaded end 63 projecting down into the hollow chamber 59.

A thin friction disk 44 is interposed between the radial arm l5 and the hub l4, and said arm is pressed downwardly against said friction disk 64 by a coiled spring ll surrounding thev reduced end 63 of said stud 62, the pressure of said spring being suiilcient to cause the arm II to be driven by the hub IS. The upper end of the spring 65 abuts against a washer ll mounted on said stud t2 and disposed against the upper end of the chamber 80, while the lower end of said spring 68' engages against a washer i1 seated upon an adjustable nut 4!, the latter being employed to vary the tension of the spring as may be desired.

The friction between the arm I! and the disk 64 is relatively weak as compared with the friction betweenthe plate It and the friction disk 3,!0 that said arm ll may be manually swung laterally in any directionwlthout disturbing the position of the hub it or the intermeshingef the gear and worm 31. However, the friction exerted by the washer I4 is strong enough to prevent slippage of the arm II with respect to the hub -16, when the latter is slowly driven by the feed mechanism.

It will be understood that this differential friction arrangement is of great importance in. the practical recording of dictation, telephone conversations, and radio programs. It is of particular importance where the recording is interrupted from time to time and must be started up quickly without permitting the needle to leave the groove where the cutting is taking place. If the friction between the recording arm I! and the friction slipping disk 44 was not weak compared to the friction between the plate It and the disk 53, the swinging of the arm It would cause play in the transmission between the turntable spindle i2 and the recording arm. This play would necessarily have to be taken up before the recording arm would start to feed. which would introduce a time lag or delay in the recording. If such a backlash occurred. the styiiu mightgrind around in the same groove and spoil both the blank and the stylus. Furthermore, such a delay would introduce an element of waiting'which could not be tolerated in the recording of passing events, such as radio programs, telephone conversations, etc.

By means of the present invention, the cutting of the record will always commence immediately as soon as the stylus is dropped into the groove, and the stylus will be positively positioned in said groove, without loss of time even when the apparatus is used by unskilled operators.

A further advantage of the present machine is that it will record the programs with perfect fldeiity even though there may be slight inaccuracies in the gears. This is due to the fact that the worm will always be held tightly in mesh with the teeth of the gear. and there will be no evidence whatsoever in the spiraling oi the recordof the point at which one tooth of the worm leaves and the next tooth takes hold. which would be the case if the friction slipping means 88 were not employed.

The ratio of the teeth on the two sets of intermeshing gears in the boxes A and B is 100 to 1 in each instance. whereby a reduction in speed of 10,000 to 1 is produced; that is, the turntable will rotate at a speed 10,000 times as fast as the angular velocity of the swinging recording arm I5.

In the making of records by either thecutting or indenting method, it is very essential-that the weight of the recording head carrying the stylus be accurately and minutely adjusted, this being accomplished by the following construction:

As best shown inFigs; 1 and 2, the outer end of the-arm I is provided with a rigid short U- shaped bracket 89, in which is pivoteda hinged block I8 by means of a pin 1| The forward end of the block is provided with an upwardly and rearwardly inclined rigid flat plate I2 adapted to receive a slidable channel plate. I3 which is adapted to be secured in any desired vertical position with respect to saidbracket 69 by means of a 'bolt 14 secured to said plate 12 and extending through an elongated slot I5 in said plate I3. A channel-shaped plate 1'8 attached to the cutting head I8 is pivoted at its lower ends to the slidable,

plate I3 by means of a pair of opposed binding screws I1; This construction permits the recording head I8 to be adjusted to any desired angular position in respect to the channel plate 18 The weight of the head I8 and its complementary supporting members is adapted to be counter-balanced by means of the force exerted by alongitudinal horizontal arm I8 attached, as

byshort screws 18a, to the underside of the hinged block 10, and extending rearwardly to apolnt intermediate the length of the arm I5. The rear end of the arm 18 has riveted thereto an upright post I9 which is adapted to pass up through an aperture 19a in the arm I5 and terminates in a rearwardly bent end 80.

A tension spring 8| is anchored at its upper end to the bent end 88, while the lower extremity of said spring is fastened to the forward end of a small vertical triangular plate 82 pivotally connected to the elevated horizontal arm 82a of an angle bracket 83 by means of a horizontal screw 88. As clearly shown in Figs. 2 and 7, the angle bracket 83 is attached to one side of the radial arm I5 by means of a horizontal screw-85 and extends upwardly and over the top of said arm I5.

.In order to vary the tension of the counter-' balancing spring 8|, provision is made of a vertical adjusting screw 88 which threadedlyengages in a tapped hole in the horizontal arm 82a of the angle bracket 83 and is provided with a knurled manually-operated head 88a at its upper head I8 engages the record I4; By turning the screw 88 downwardly,.the reverse action will take place; i. e., the tension of the spring 8| will be lessened, and the stylus pressure on the record will be increased due to the weight of the recordingheadl8. r

In case it is desired to temporarily hold the recording head I8 in elevated inoperative position with the stylus I9 out of contact with the record ll, provision is made of a vertical upstanding pin 88 attachedv to an intermediate part of the counter-balance arm I8, and adapted to project up through a suitable aperture 89a in the' radialarm I5. The upper end of the pin is adapted to abut against the underside of a circular knurled cam head 90 integral with the 2 clockwise direction as viewed in Fig 2 about its pivot pin II, and the recording head I8 will be maintained in an elevated position, holding the needle I9out of contact with the record l4. When, however,-it is desired to cause the recording stylus I9 to engagethe surface of the record, it will only be necessary to rotate the cam head 98 until the high flat section 98 is positioned in alinement with the pin 89. The arm 18 will then be permitted to rock freely in a clockwise d rection and allow the head I8 to move into recording position.

The pressure of the stylus I9 upon the record may also be adjusted by means of a solidknurled nut 95 which may be manually moulded along the 'length of a threaded rod 96 extending from the outer face of the recording head I8. Thus, by moving-the nut 95 outwardly upon the rod 98, the force exerted by the stylus needle I9 upon 95 will generally be employed as it will assist in obtaining the greater pressure required.-

As shown in Fig. 1, an electrical conductor cord 91 is provided for connecting the recording head I8 with a prong plug 88-which is adapted to be inserted in a suitable socket 99 connected to an amplifier or any other suitable source of electrical vibrations.

. While there has been disclosed in this specif'ication one form'in which the invention may be embodied, it is to be understood that this form is shown for the purpose of illustration only,

8 all the modifications and embodiments coming within thescope of the following claims.

Having thus fully described the invention, what is claimed as new and for which it is desired to secure Letters Patent, is:

1. In a sound recording mechanism, a disk reoord turntable, a swinging recording arm extending over said table, feed means to swing said recording arm slowly over the surface of the record to be recorded, said feed means including a driven spindle, a hub, relatively weak friction slipping means for connecting said hub with said arm, and relatively strong friction means for braking said hub, whereby said arm may be swung with respect to said hub without introducing backlash in said feed means.

2. Ina sound recording mechanism, a disk recrecording arm sldwly over the surface of the record turntable, a swinging recording arm extending over said table, feed means to swingsaid recording arm slowly over the suriaceof the record to be recorded, said feed means including a'.

said arm, relatively strong friction means for exerting a braking action upon said hub, whereby said arm may be swung with respect to said hub without introducing backlash in saidfeed means, and spring means associated with said spindle for varying the pressure on said strong friction slipping means.

3. In a sound recording mechanism, a disk record turntable. a swinging recording arm extending over said table, feed means to swing said ord to be recorded, said feed meansincluding a driven spidle, a hub, relatively weak friction slipping means for connecting said hub with said arm, and relatively strong friction means for connecting said hub with said feed means, whereby said arm may be swung with respect to said hub without introducing backlash in said feed means, and adjustable spring means associated with said spindle for varying the pressure on said strong friction slipping means.

'4. In a sound'recording machine, a power driven spindle, a turntable mounted for rotation with said spindle, a recording arm for swinging across said turntable, a speed reduction feed mechanism for driving said swinging arm, a weak friction connection between said feed mechanism and said am to permit said arm to be manually swung about its axis to any desired point on the record, and a relatively strong friction brake for said feed mechanism to prevent backlash therein and permit the recording to be resumed without delays occasioned by the taking up of backlash.

5. In a sound recording machine, a power driven spindle, a turntable mounted for rotation with said spindle, a swinging arm extending across said turntable, a continuously driven speed reduction fed mechanism connected to said spin die and said swinging arm, a relatively weak friction means for driving said arm from said feed mechanism, and a relatively strong braking means for said feed mechanism to permit said arm to be manually swung about its axis to any desired point without introducing backlash into said feed mechanism which would have to be taken up before again recording.

6. In a sound recording machine, a power driven spindle, a turntable mounted for rotation with said spindle, a swinging arm adapted to extend across said turntable, a speed reduction feed mechanism, a relatively weak friction driving connection between said spindle and said arm, and a relatively strong braking means for said spindle to permit said arm to be manually swung about its axis to any'desired point without introducing backlash into the mechanism for driving said spindle.

'7. Ina sound recording machine, a frame, a record supporting turntable rotatable adiacent said frame, a driving spindle for operating said turntable, a swinging arm having a recording head at its free end supported adjacent said record, a feed mechanism, a relatively weak friction slipping means for driving said swinging arm from said feed mechanism and permitting said arm to be manually positioned at any desired point, and a relatively strong braking means for said feed mechanism to prevent backlash therein and permitting the recording to be resumed at any desiredpoint without introducing delay occasioned by the taking up of backlash.

8. In a sound recording machine, a power-driven spindle, a turntable mounted for rotation with said spindle, a pivoted recording arm a'dapted to swing across said turntable, a speed reduction feed mechanism connected to said spindle and said swinging arm, said mechanism comprising two speed reductions connected in series, the final reduction including an intermeshing worm and gear, a relatively powerful friction slipping means applied to said gear to take up backlash in the transmission, and relatively weak friction slipping means for causing said recording arm to be driven from said gear and permit said arm to be moved to. any desired point on the record without introducing delay when recording is resumed due to the taking up of backlash.

9. In a sound recording mechanism, a disk record turntable, a swinging recording arm extending over said table, feed means to swing said recording arm slowly over the surface of the record to be recorded, said feed means including a driven spindle, relatively weak friction slipping means for connecting said spindle with said arm, and relatively strong friction means for braking said spindle,. whereby said arm may be swung with respect to said spindle without introducing,

backlash in said feed means.

10. In a sound recording mechanism, a disk record turntable, a swinging recording arm extending oversaid table, feed means to swing said recording arm slowly over the surface of the 

